I am a Catholic (Well, according to some I'm not but I'll not go into that), but I am somewhat leaning towards agnosticism. I am one hundred percent certain that it is impossible to disprove the existence of God. On the contrary, using Reason as guidelines, I'm fairly certain he does in fact exist, though it is nearly impossible to prove. There has only been one proof that I have never seen disproved, and that would be on the Christian side, coming from the greatest philosopher to live, Thomas Aquinas.
If you have not read and/or interpreted his 5 proofs on the existence of God, I would highly recommend you doing so.